Rainbow Electronics ATmega8HVD - Manual (Page 90)

90
8052B–AVR–09/08
ATmega4HVD/8HVD
17. ADC - Analog-to-Digital Converter
17.1 Features
• 10-bit Resolution
• 78 µs Conversion Time @ clk
ADC
= 167 kHz
• Up to 13 kSPS at Maximum Resolution
• External Input Channel with 0 - 5V Input Voltage Range
• External Input Channel (ADC0) with 0 - 1V Input Voltage Range
• Internal Temperature Sensor Input Channel
• 1.1V ADC Reference Voltage (typical value)
• Interrupt on ADC Conversion Complete
• Sleep Mode Noise Canceler
The ATmega4HVD/8HVD features a 10-bit successive approximation ADC. The single-ended
voltage inputs refer to 0V.
The ADC contains a Sample and Hold circuit which ensures that the input voltage to the ADC
is held at a constant level during conversion. A block diagram of the ADC is shown in
Figure
17-1 .
Internal reference voltage of nominally 1.1V is provided on-chip. External input on PV1 pin is
divided by 5 internally to be within the range of the internal reference votlage.
Figure 17-1. Analog-to-Digital Converter Block Schematic
ADC CONVERSION COMPLETE IRQ
8-BIT DATABUS
15 0
ADC CONTROL & STATUS
REGISTER (ADCSRA)
ADC DATA REGISTER
(ADCH/ADCL)
ADIE
ADSC ADEN
ADIF
ADIF
CONVERSION LOGIC
10-BIT DAC
+
-
SAMPLE & HOLD
COMPARATOR
INTERNAL 1.1V
REFERENCE
PV1
GND
ADC[9:0]
1/5
TEMPERATURE
SENSOR
AGND
ADTEMP
MUX
ADC0